The present invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument such as an electronic percussion, which detects a performance operation based on an operation amount, e.g., a vibration amount representing a strength, speed, depth, and the like of a performance operating member, e.g., a string or a drum pad.
As shown in FIG. 23, an electronic percussion 1 of this type has pads PAD1 to PAD6 as six performance operating members 3 which are arranged on a board 2. When a performer strikes one of the pads PAD1 to PAD6 with a stick, the corresponding one of the pads PAD1 to PAD6 generates performance operation data such as striking strength, speed, depth, and the like based on a vibration in accordance with its performance operation amount, and the performance operation data is converted to electrical performance operation detection data. Then, a percussion tone assigned to the corresponding one of the pads PAD1 to PAD6 is produced in accordance with a tone generation condition set by various setting operating members on a setting operation unit 4.
For example, as percussion tones, a bass drum tone, cymbal tone, snare drum tone, high hat open tone, and high hat close tone can be respectively assigned to the pads PAD1 to PAD6.
When the performance operating members 3 operated by the performer have relatively large operation surfaces like the pads PAD1 to PAD6, and the performer strongly strikes one (e.g., pad PAD1) of the pads PAD1 to PAD6, the corresponding pad PAD1 is vibrated (this is called a "self vibration"). Thus, operation data such as an operation strength can be inputted, and the remaining pads PAD2 to PAD6 arranged on the board 2 are vibrated upon influence of the vibration of the pad PAD1 (this is called a "parasitic vibration").
In practice, the following technique can be employed. In order to accurately detect a performance operation state of the pads PAD1 to PAD6 based on such a vibration, an envelope signal J2 shown in FIG. 24B is formed based on a vibration detection signal J1 shown in FIG. 24A. When a peak value appears in the envelope signal J2, it is determined that the performance operation is made, and a performance operation data fetch signal J3 is generated as shown in FIG. 24C.
However, when performance operation data is obtained by this technique, if the pads PAD1 to PAD6 are abnormally strongly struck, the vibration detection signal J1 does not have a waveform which has only on peak and is naturally attenuated, and an abnormal vibration detection signal J1X which generates second and third peaks following the first peak may be generated.
In this case, every time a peak value appears in the abnormal vibration detection signal J1, a performance operation data fetch signal J3X is generated, and an abnormal musical tone is generated. Thus, the musical tone may become unnatural.
Assume that a conventional electronic percussion is struck using a stick in practice, for example, that a performer holds sticks with his hands and strikes the pads PAD1 to PAD6. In this case, if the performer strikes one pad with one stick, and immediately thereafter (after the lapse of a very short period of time), strikes the same pad with the other stick (i.e., he successively strikes the same pad), in order to strike the corresponding pad thereafter, i.e., to perform a performance operation of a third strike, he must release one or both the sticks from the pad from a state wherein the sticks are in contact with the surface of the pad.
In the electronic percussion, when the same pad is successively struck twice, if a percussion tone is produced during a time interval from the timing of the second strike until the stick is returned to an original position, the produced tone inevitably sounds unnatural.
When a drum or cymbal as an acoustic percussion is struck with two sticks, no tone is generated between the second and third strike timings. However, in the electronic percussion, if a musical tone which does not maintain the above-mentioned time interval is produced, it is discriminated as an unnatural percussion tone.
The above-mentioned parasitic vibration occurs if the pads PAD1 to PAD6 are a drum, cymbal, and the like as acoustic percussions, and it is undesirable to prevent a parasitic vibration in comparison with the acoustic percussions.
Considering a drum set as an acoustic percussion, if one percussion, e.g., a bass drum is struck by a beater, since the vibration of the struck vibration skin head has considerably large energy, other drums and cymbals cause the parasitic vibration. As a result, the produced tone can be listened to as a synthesized performance tone of the drum set including a state wherein a plurality of percussions are vibrated by the parasitic vibration.